IGX Frame relay

[gauravprakash]

Hi,

I have two IGX 8440 with 1 MB Frame Relay port capacity connceted each side, rest is for voice. PLease help me out with bandwitdh parameters.

MIR 800/800

CIR 800/800

VC Q Depth 65535/65535

PIR 800/800

Cmax 10/10

ECN QThresh 65535/65535

QIR 800/800

this is the cuurent confg both side. Can I increase the PIR to port speed i.e 1024 kbps without changing the other parameter. Also, %utl is set to 60/60. Can I change %utlz to 100/100, . Please suggest what is the best working configuration.

FST is set to Y (yes).

I tried to change the only the MIR,CIR,PIR,QIR to 900/900, on one side, the Framerelay connection got down.

Has it to be same one other side,

Please suggest the config for maximum utlization.(1 Mb FR).

Somebody told me PIR should be near to CIR/MIR?? Is is true??

[owillins]

You will get a better performance if you increase the PIR,MIR and QIR values (except for CIR, which doesn't do anything in terms of actual network performance). As the PIR is the max bandwidth the connection will get, it should be chosen accordingly.The MIR should be set at the minimum, 19.2kbps or 9.6kbps might be OK.

[marikakis]

If there is no congestion in your network and bandwidth is plenty, you will get your PIR.

But, if congestion does occur, your guaranteed rate is MIR*util.

The problem with MIR*util having high value is that

your connection might fail to reroute under current path failure circumstances.

If you have no available paths for such rerouting to ever occur and you do not oversubscribe,

then I suppose you should concentrate on raising the product of the values MIR, util.

M.

[gauravprakash]

Traffic gets slow when the total bandwith used comes near to 500kbps. Is it due to the %utl set to 60%.

?

[marikakis]

First, I want to clarify that when I wrote MIR*util, by util I meant

the percentage and not the parameter actually configured.

I think you understood what I meant, but the way I wrote it wasn't accurate.

You have an MIR of 800kbps and util 60, so 800*0.6=480kbps

If there is congestion in your network, you will probably see drops/delays

when that value is approached.

(You have also set CIR, PIR, QIR to the same value of 800,

but MIR is what counts when congestion occurs.)

util is supposed to be an estimation of the expected utilization of the VC,

and a hint to the network to reserve resources for the VC accordingly.

If the estimation is incorrect, then the network is misinformed

and you will pay the consequences when many VCs start requesting

their theoretical share of bandwidth.

If you can increase the util, then do it

if this VC is more important to you relatively to the others.

If you change the util and the VC fails to route,

you can try adjusting the util of less important VCs to lower values

in order to free up some bandwidth to route the connection.

BTW, fst can be very aggressive sometimes.

If you make it fr, there is a chance you will get better results. It depends.

Nevertheless, you cannot avoid bad performance overall

if you do not have enough bandwidth for your needs.

M.